Question: 4 folders cost $3.76. Which equation would help determine the cost of 8 folders?
Answer: There are several equations that could help determine the cost, each with a slightly different approach. We know the cost of 4 folders. We want to know the cost of 8 folders. We can write the numbers of folders as a proportion: $\dfrac{4}{8}$ We know 4 folders costs $3.76. We can let $x$ represent the unknown cost of 8 folders. The proportion of these costs can be expressed as: $\dfrac{\$3.76}{x}$ The cost changes along with the number of folders purchased, and so the two proportions are equivalent. $\dfrac{4}{8} = \dfrac{\$3.76}{x}$